The proposed work involves the development of new amino-protecting groups for use in the synthesis of sensitive biologically active materials such as pharmaceuticals, peptides, proteins and polynucleotides. For ease of operation following the de-blocking procedure emphasis is placed on groups leading to 1. volatile or b. totally insoluble by-products. Current study will involve 2, 7-disubstituted derivatives of the 9-fluorenylmethyloxycarbonyl group as base-sensitive systems. Analogous systems with the fluorene nucleus replaced by a cyclic sulfone unit are potentially capable of being de-blocked by very mild bases (pyridine). The beta-trimethylsilylethyloxycarbonyl group which is cleaved by fluoride ion will be modified for even more facile de-blocking. Solvolytically de-blocked halo-urethanes and halo-amides will be studied in connection with the development of groups capable of attachment to polymers which can release the amino component, e.g., a drug, at a controlled rate in body tissues. Finally new techniques of de-blocking will make use of polymeric de-blocking agents so that after release of a desired amine simple filtration and evaporation will give the substance in question without elaborate work-up.